Remarkably, over 6% of sporadic ALS/FTD cases and over 37% familial ALS/FTD cases are caused by the expansion of the GGGGCC hexanucleotide repeat in the first intron of the C9ORF72 gene (Majounie et al., 2012). This evidence concerns the gene C9orf72 and amyotrophic lateral sclerosis.